If you want to travel at a predetermined speed, rather than in a predetermined travel time, do the above computations with travelTime set to some arbitrary value (1.0f would work fine, so you could simply eliminate the division). Then compute this factor:

(Note that you'll be dividing by zero if xSpeed and ySpeed are both 0, but that simply indicates that the current and target locations are identical. If that's a possible condition, you should include an appropriate check.) Finally, readjust xSpeed and ySpeed by the factor:

xSpeed *= factor;
ySpeed *= factor;

Note that by setting travelTime to 1, this is just a sneaky way of multiplying the predetermined speed by the sine and cosine of the angle that the travel direction makes with the x axis without mentioning trigonometry at all. :)